The present invention relates generally to a manner by which to place an emergency call utilizing a radio communication system, such as mobile station operable in a cellular communication system. More particularly, the present invention relates to apparatus, and an associated method, by which selectably to place an emergency call by way of any communication system in which a mobile station is operable. If the emergency call is unable to be completed by way of one of the communication systems, attempts are made to place the call by way of another communication system in which the mobile station is operable. The possibility that an emergency call might not be able to be completed due, e.g., to system congestion, or other communication difficulty, is reduced through operation of an embodiment of the present invention as use of alternative communication systems to place the call is permitted.
A communication system is formed, at a minimum, of a sending station and a receiving station interconnected by way of a communication channel. Information to be communicated by the sending station to the receiving station is converted into a form to permit its communication upon the communication channel, thereafter to be received at the receiving station.
A radio communication system is a type of communication system in which the communication channel is formed of a radio link formed between the sending and receiving stations. The radio link is defined upon a portion of the electromagnetic spectrum. In contrast, conventional wireline communication systems require a wired connection between the sending and receiving stations upon which to form a communication channel therebetween. Because radio links are utilized in a radio communication system, the need for conventional wireline connections between the sending and receiving stations in a conventional wireline communication system are obviated. A radio communication system, therefore, inherently permits increased communication mobility in contrast to conventional wireline systems. That is to say, radio communication systems can be utilized to effectuate communications therethrough in situations in which use of a conventional wireline communication system would be impractical.
A radio communication system, however, typically, is bandwidth-limited. Regulatory bodies which allocate usage of the electromagnetic spectrum allocate only a limited amount of the electromagnetic spectrum for communications in a particular radio communication system. Because the spectrum allocation for use by a particular system is limited, communication capacity increase of a radio communication system is limited by such allocation. Efforts are made, therefore, to construct a radio communication system in manners which efficiently utilize the allocated spectrum.
A cellular communication system is exemplary of a radio communication system. Mobile communication systems make relatively efficient use of the spectrum allocated thereto. Signals generated during operation of the mobile communication system are of relatively low power levels. Because of the use of low-power signals, the same channels can be reused throughout a mobile communication system according to a cell reuse plan. Concurrent use of the same channels is permitted according to the cell reuse plan, thereby to effectuate concurrent communications on the same channels by different communication station pairs at different locations throughout the area encompassed by the mobile communication system.
Generally, first-generation, cellular communication systems utilize analog communication techniques, such as FDM (Frequency Duplex Multiplexing) techniques. Even utilizing cell reuse plans, however, such cellular communication systems are sometimes utilized at maximum capacities, particularly at certain-times-of-day and within certain cells of the communication systems.
Digital communication techniques have been utilized in various so-called, second-generation, cellular communication systems. Through the use of digital communication techniques, more efficient utilization of the bandwidth allocated to the communication system is possible, thereby permitting an increase in the communication capacity of the communication system.
Such communication systems, in many instances, have been overlayed upon existing communication systems. That is to say, in a geographical area in which one cellular communication system is already installed, another communication system is also installed to encompass the same, or similar, geographical area. Mobile stations have been constructed to permit their operation in a selected system of two or more of such communication systems. Such mobile stations are sometimes referred to as being multi-mode mobile stations.
While a mobile station is utilized by a user for any of many varied communication purposes, use of a mobile station is perhaps of greatest benefit in the event of an emergency situation. In an emergency situation, the mobile station can be utilized by the user to request emergency assistance. In many parts of the United States, for instance, the digits 9-1-1 are associated with an emergency dispatch station. By entering such digits, the user of the mobile station is generally capable of soliciting a request for emergency assistance.
However, to complete the request for emergency assistance, bandwidth must be available to complete the call. Situations may develop in which communication capacity in one system prevents the completion of the emergency call. If the mobile station is operable in more than one communication system, if a manner could be provided by which to permit the emergency call to be placed pursuant to alternative communication systems, an increased probability that the emergency call can be successfully completed would result.
It is in light of this background information related to operation of a mobile station to place an emergency call that the significant improvements of the present invention have evolved.
The present invention, accordingly, advantageously provides apparatus, and an associated method, by which to place an emergency call utilizing a radio communication system such as by utilizing a mobile station operable in a cellular communication system.
Through operation of an embodiment of the present invention, a manner is provided by which selectably to place an emergency call by way of any communication system in which the mobile station is operable. When the mobile station is operable in more than one communication system, if the emergency call is unable to be completed by way of one of the communication systems, attempts are made to place the call by way of another communication system.
By increasing the number of communication systems in which an emergency call can be placed, the possibility of an emergency call might not be able to be completed is reduced. System congestion, or other communication difficulties in one communication system might well not be replicated in another of the communication systems. Thereby, the emergency call can be completed in the alternate communication system.
In one aspect of the present invention, a mobile station is selectably operable in at least two radio communication systems, such as a cellular communication system operated by a first operator and a cellular communication system operated by a second operator. One of the communication systems forms a presently-acquired communication system in which the mobile station is registered to be operable. When the user of the mobile station initiates an emergency call, the mobile station is operable first to attempt to complete the call by way of the presently-acquired communication system. If the call can be completed, conventional operation of the mobile station is effectuated. If, conversely, the call cannot be completed utilizing the presently-acquired communication system, through operation of an embodiment of the present invention, the call is attempted by way of another communication system, such as the cellular communication system operated by another operator. By providing the opportunity alternately to place the emergency call by way of the other communication system, the possibility that the emergency call shall not be able to be completed is reduced.
In another aspect of the present invention, a determination is made as to whether the emergency call is completed. If a determination is made that the emergency call has not been completed, that is to say, a connection between the mobile station and the emergency station associated with the emergency call is not completed, a decision is made as to whether to reattempt to complete the emergency call pursuant to the presently-acquired communication system. A decision is made, for instance, to reattempt to place the emergency call pursuant to the presently-acquired communication station a selected number of times. If a decision is made not to reattempt to complete the emergency call pursuant to the presently-acquired communication system, an attempt, instead, is made to complete the emergency call upon a channel of another communication system.
In another aspect of the present invention, a decision to reattempt to complete the emergency call by way of one of the communication systems is dependent upon the time period permitted within which to place the emergency call. If the time period has expired, the decision is made to utilize a channel of another communication system by which to attempt to complete the emergency call.
In another aspect of the present invention, a mobile station is operable selectably in at least three communication systems, such as a cellular communication system operated by a first operator, a second cellular communication system operated by a second operator, and PCS (Personal Communication Service) communication system. If, when an emergency call placed pursuant to a presently-acquired communication system cannot be effectuated and, thereafter, the emergency call can also not be placed by way of a first alternate communication system, an attempt is thereafter made to place the emergency call by way of a second alternative communication system. Thereby, the likelihood that an emergency call cannot be completed by way of the mobile station is further reduced.
In these and other aspects, therefore, apparatus, and an associated method, is provided for facilitating completion of an emergency call placed at a mobile station. The mobile station is operable in a first radio communication system in which a first set of channels is utilized in placement of the emergency call. And, the mobile station is operable in at least a second radio communication system in which at least a second set of channels is utilized in placement of the emergency call. A preferred list of channels is selected from at least one of the first set and the second set utilized by the mobile station first to attempt the completion of the emergency call. A selector is coupled to receive indications of non-successful completion of the emergency call through utilization of the preferred list of channels. The selector is operable responsive thereto to select at least one additional channel to be utilized by the mobile station to attempt the completion of the emergency call. The at least one additional channel is selected from the first set and the second set and is not contained in the preferred list of channels.
A more complete appreciation of the present invention and the scope thereof can be obtained from the accompanying drawings which are briefly summarized below, the following detailed description of the presently-preferred embodiment of the present invention, and the appended claims.